Retrospective analysis of canine fecal flotation and coproantigen immunoassay hookworm positive results in Greyhounds and other dog breeds.

Recent studies demonstrated that Greyhounds are commonly infected with Ancylostoma caninum and these infections have been shown to be resistant to anthelmintics. This study evaluated samples submitted to a commercial reference laboratory (IDEXX Laboratories) for canine fecal flotation zinc sulfate centrifugation and coproantigen immunoassay between January 1, 2019, and July 30, 2023 for evidence that Greyhounds were more often positive for Ancylostoma spp. (hookworms) compared to other breeds. The purpose of the study was to determine if Greyhounds were more likely to be hookworm-positive compared to other breeds, if Greyhounds on preventives with efficacy against hookworm infections are more likely to test positive than other breeds, if their infections take longer to resolve, to estimate how long this takes and to assess whether the proportion of hookworm positive tests for all breeds is increasing over time. Records of 25,440,055 fecal results were obtained representing 17,671,724 unique dogs. Of these, 49,795 (∼0.3%) were Greyhounds. The overall odds ratio (OR) of 15.3 (p < 0.001) suggests that Greyhounds are at significantly higher risk than other breeds for hookworm positive float findings, and the OR of 14.3 (p < 0.001) suggests significantly higher risk for hookworm antigen positive results. The median time to negative testing event from the Turnbull distribution estimate was in the interval of 1-2 days for other breeds and 71-72 days for Greyhounds. These results provide evidence that anthelmintic resistant A. caninum strains may be having population-level impacts on the frequency and duration of infections in Greyhounds. The findings have broader health implications beyond Greyhounds as MADR A. caninum strains could spread to other breeds and even pet owners.

Spatial and risk factor analyses of vector-borne pathogens among shelter dogs in the Eastern United States.

BACKGROUND: Vector-borne infections pose significant health risks to humans, domestic animals, and wildlife. Domestic dogs (Canis lupus familiaris) in the United States may be infected with and serve as sentinel hosts for several zoonotic vector-borne pathogens. In this study, we analyzed the geographical distribution, risk factors, and co-infections associated with infection with Ehrlichia spp., Anaplasma spp., Borrelia burgdorferi, and Dirofilaria immitis in shelter dogs in the Eastern United States. METHODS: From 2016 to 2020, blood samples from 3750 shelter dogs from 19 states were examined with IDEXX SNAP® 4Dx® Plus tests to determine the seroprevalence of infection with tick-borne pathogens and infection with D. immitis. We assessed the impact of factors including age, sex, intact status, breed group, and location on infection using logistic regression. RESULTS: The overall seroprevalence of D. immitis was 11.2% (n = 419/3750), the seroprevalence of Anaplasma spp. was 2.4% (n = 90/3750), the seroprevalence of Ehrlichia spp. was 8.0% (n = 299/3750), and the seroprevalence of B. burgdorferi was 8.9% (n = 332/3750). Regional variation in seroprevalence was noted: D. immitis (17.4%, n = 355/2036) and Ehrlichia spp. (10.7%, n = 217/2036) were highest in the Southeast while seroprevalence for B. burgdorferi (19.3%, n = 143/740) and Anaplasma spp. (5.7%, n = 42/740) were highest in the Northeast. Overall, 4.8% (n = 179/3750) of dogs had co-infections, the most common of which were D. immitis/Ehrlichia spp. (1.6%, n = 59/3750), B. burgdorferi/Anaplasma spp. (1.5%, n = 55/3750), and B. burgdorferi/Ehrlichia spp. (1.2%, n = 46/3750). Risk factors significantly influenced infection across the evaluated pathogens were location and breed group. All evaluated risk factors were significant for the seroprevalence of D. immitis antigens. CONCLUSIONS: Our results demonstrate a regionally variable risk of infection with vector-borne pathogens in shelter dogs throughout the Eastern United States, likely due to varying distributions of vectors. However, as many vectors are undergoing range expansions or other changes in distribution associated with climate and landscape change, continued vector-borne pathogen surveillance is important for maintaining reliable risk assessment.

Heartworm 'lack of effectiveness' claims in the Mississippi delta: computerized analysis of owner compliance--2004-2011.

A retrospective medical record review was conducted to identify factors from veterinary clinic medical records that may have contributed to suspected ineffectiveness of a heartworm preventive product. Patient records of 271 dogs, comprising 301 instances of positive heartworm antigen test results while the dogs were receiving heartworm preventive were evaluated. Nineteen veterinary practices in 17 counties and parishes in Arkansas, Louisiana, Mississippi, and Tennessee participated in the study. Records were selected by the veterinary clinics as representative of cases of suspected lack of effectiveness for a heartworm preventive, and for which an owner satisfaction claim had been filed with the manufacturer. Medical record data were entered into a software program, and a graphic representation was created to facilitate analysis of whether pet owners had purchased sufficient heartworm preventive for the dog to be compliant during the period when infection with Dirofilaria immitis could have led to the positive heartworm antigen test result for that patient ("window of infection"). In 243 (80.7%) cases, there was insufficient heartworm preventive purchased, leading to a gap in protection during the "window of infection". In only five cases (1.7%) there were no purchase lapses or extenuating circumstances (underdosing of medication, multiple purchase gaps outside the established window of infection, or dogs have been diagnosed with heartworm infection more than once during the period studied). Half the cases were from multiple-dog households, and in many of these households, sharing of product between pets was acknowledged. In another 28% of the cases from multiple-dog households, more product was purchased than was needed for one dog, suggesting that the product was being shared between more than one pet. In most cases, there was at least one reason that a dog did not receive sufficient heartworm preventive product, placing the dog at risk of developing an infection with mature heartworms. Several actions were identified that veterinary clinics can take to improve heartworm disease prevention in their patients.